The Milky Way’s Black Hole Shoots Out Brightest Flare Ever

This false-color image shows the central region of our Milky Way Galaxy as seen by Chandra. The bright, point-like source at the center of the image was produced by a huge X-ray flare that occurred in the vicinity of the supermassive black hole at the center of our galaxy.
Image: NASA/MIT/F. Baganoff et al.

For some unknown reason, the black hole at the center of the Milky Way galaxy shoots out an X-ray flare about once a day. These flares last a few hours with the brightness ranging from a few times to nearly one hundred times that of the black hole’s regular output. But back in February 2012, astronomers using the Chandra X-Ray Observatory detected the brightest flare ever observed from the central black hole, also known as Sagittarius A*. The flare, recorded 26,000 light years away, was 150 times brighter than the black hole’s normal luminosity.

What causes these outbursts? Scientists aren’t sure. But Sagittarius A* doesn’t seem to be slowing down, even though as black holes age they should show a decrease in activity.

Earlier this year, a group of researchers said that the outbursts may come from asteroids or even wandering planets that come too close to the black hole and they get consumed. Basically, the black hole is eating asteroids and then belching out X-ray gas.

Astronomers involved in this new observation seem to concur with that line of thinking.

“Suddenly, for whatever reason, Sagittarius A* is eating a lot more,” said Michael Nowak, a research scientist at MIT Kavli and co-author of a new paper in the Astrophysical Journal. “One theory is that every so often, an asteroid gets close to the black hole, the black hole stretches and rips it to pieces, and eats the material and turns it into radiation, so you see these big flares.”

Astronomers detect black holes by the light energy given off as they swallow nearby matter. The centers of newborn galaxies and quasars can appear extremely bright, giving off massive amounts of energy as they devour their surroundings. As black holes age, they tend to slow down, consuming less and appearing fainter in the sky.

“Everyone has this picture of black holes as vacuum sweepers, that they suck up absolutely everything,” says Frederick K. Baganoff, another co-author from MIT. “But in this really low-accretion-rate state, they’re really finicky eaters, and for some reason they actually blow away most of the energy.”

While such events like this big blast appear to be relatively rare, Nowak suspects that flare-ups may occur more frequently than scientists expect. The team has reserved more than a month of time on the Chandra Observatory to study Sagittarius A* in hopes of identifying more flares, and possibly what’s causing them.

“These bright flares give information on the flaring process that isn’t available with the weaker ones, such as how they fluctuate in time during the flare, how the spectrum changes, and how fast they rise and fall,” said Mark Morris from UCLA. “The greatest importance of this bright flare may be that it builds up the statistics on the characteristics of strong flares that can eventually be used to [identify] the cause of such flares.”

Even more intriguing to Baganoff is why the black hole emits so little energy. In 2003, he ran the very first observations with the then-new Chandra Observatory, and calculated that, given the amount of gas in its surroundings, Sagittarius A* should be about a million times brighter than it is — a finding that suggested the black hole throws away most of the matter it would otherwise consume.

The physics underlying such a phenomenon remain a puzzle that Baganoff and others hope to tease out with future observations.

“We’re really studying the great escape, because most of the gas escapes, and that’s not what we expect,” Baganoff says. “So we’re piecing out the history of the activity of the center of our galaxy.”

Paper: Chandra/HETGS Observations of the Brightest Flare seen from Sgr A*

12 Responses

The region around the Milky Way black hole consists of a number of stars orbiting the BH at 1000km/sec range. It is not hard to imagine that if there are planets associated with the formation of these stars that the gravitational perturbations in this region have stripped them from their stars. So this region is a complicated system of stars, planets and asteroid bodies in orbit around the BH. Smaller masses are more likely to be shot towards the black hole by such perturbations.

It is actually rather hard to get something into a black hole. It has to be directed right towards the BH, or there must be some attenuating mechanism that degrades orbits.

I figure there may be a lot of planetary junk down there. Asteroids, comets, dwarf planets, terrestrial planets and maybe gas giants could be orbiting the BH. Any stars that got too close might have lost some companions or leftover bits.

If you shoot something at a black hole it must come within 3GM/c^2 of the black hole in order to fall in. If your projectile approaches the black hole with a larger distance, called the impact parameter, it will then go into orbit around the black hole and not fall in. If your projectile is the only other mass than the black hole this orbit is “eternal.” Since a black hole is very small for its mass it takes good aim to hit the black hole. If the sun were a black hole it would only be about 2km in radius, so if you shoot from a distance of tens of millions of kilometers you have to have a good aim.

when i calculate earth’s radius and mass if it turns into a black hole then it is radius become greater than or equal to 8.9*10^-3 m. and its mass greater than or equal to 43.19*10^32 kg. by using equation of escape velocity GM/R greater than or equal to C^2

Well, from info on the net it appears that there is a ratio of mass between the galactic center and rest. so is the ratio in equilibrium?

I propose that the magnetic field ages in place allowing the relaxation of the center and subsequent matter is not energetically ejected axially but lazily horizontally thru the equatorial center of the galaxy to the rim where science notes new blue stars form. I propose in my paper Galactic Winds that the magnetic field deteriorates to such an extent that the nucleus looses it ability to keep gas pressurized and the gas fog at the center and the rim from mass into matter fog allows the galaxy to become a gas cloud with the spiral form deteriorating inside the gas fog cloud. This aging is the common end of galaxies.

As the gas fog cloud is cooler next to cosmic space, we see cold gas clouds in the cosmos. These starless darks are the ends of galaxies.